The subject matter disclosed herein relates to imaging systems, and more particularly, to a collimator for an imaging detector assembly.
In computed tomography (CT), X-ray radiation spans a subject of interest, such as a human patient, and a portion of the radiation impacts a detector where the image data is collected. In digital X-ray systems a photodetector produces signals representative of the amount or intensity of radiation impacting discrete pixel regions of a detector surface. The signals may then be processed to generate an image that may be displayed for review. In the images produced by such systems, it may be possible to identify and examine the internal structures and organs within a patient's body. In CT systems a detector array, including a series of detector elements, produces similar signals through various positions as a gantry is displaced around a patient, allowing volumetric reconstructions to be obtained.
A typical CT detector may include a collimator assembly including collimator modules disposed adjacent to each other (e.g., edge to edge). However, these collimator modules may experience phenomena that results in artifacts in the image data. For example, module to module thermal mechanical movement (e.g., due to expansion) may lead to channel to channel variation resulting in image artifacts such as rings and bands. In addition, g-loading motion artifacts may also occur. In certain collimator assemblies, adjacent collimator modules each have a plate on adjacent edges. This type of collimator assembly may require tight tolerance control due to small gaps between these adjacent plates on the adjacent edges across sensor boundaries or it may require larger sensor to sensor gaps resulting in reduction of image resolution. In other collimator assemblies, collimator modules may share a scatter plate across module boundaries. Utilization of a shared plate may result in sensor to sensor boundary issues such as gain shift due positional change in the shared plate.